'Inhaling Versions of COVID-19 Vaccine Also under Trials' - How it Works?

As the race to developing the vaccine to fight the novel coronavirus intensifies, from across the globe, British researchers have started trials of inhaling vaccines which can directly be given to the respiratory tract, to develop immunity against this new viral infection.
The Imperial College London is testing two versions of this vaccine developed by Oxford University. Currently all the vaccines that are being tested on humans are only through intramuscular injection. However, according to scientists at the Imperial College, the vaccines which are given via inhalation has greater potential and might trigger a stronger immune response to the infection.
“We have already shown that (Oxford vaccine) ChAdOx1 nCoV-19 (AZD1222) is safe and induces strong immune responses after intramuscular injection,” said Sarah Gilbert from the University of Oxford.
“Delivering the vaccine to the respiratory tract instead may be a good approach to inducing immune responses in the best place to enable a rapid response after exposure to airborne virus,” Reuters reported.
“A number of groups around the world are currently working on clinical trials for Covid-19 vaccines. However, these trials are unlikely to tell us anything about the localised response in the nose, throat and airways - where the virus primarily attacks and invades cells,” Professor Robin Shattock, research lead at the university, was quoted as saying by the BBC.
“It may well be that one group has the right vaccine but the wrong delivery method. And only trials such as this will be able to tell us that.”